Creating appealing characters has been one essential desire for feature animation. One challenging aspect is the production of life-like deformations for soft tissues comprising both humans and animals. In order to provide the necessary control and performance for an animator, such deformations are typically computed using a skinning technique and/or an example based interpolation method. Meanwhile, physical simulation of flesh-like material is usually avoided or relegated to an offline process due to its high computational cost. However, simulations create a range of very desirable effects, like squash-and-stretch and contact deformations. The latter is especially desirable as it can guarantee pinch-free geometry, which is important for subsequent simulations like cloth and hair.
Although the benefits of solving the equations of the underlying physical laws for character deformation are clear, computational methods are traditionally far too slow to accommodate the rapid interaction demanded by animators. Many simplified approaches to physical simulation can satisfy interactivity demands, but any such approach must provide all of the following functionality to be useful in production: (1) robustness to large deformation, (2) support for high-resolution geometric detail, and (3) fast and accurate collision response (both self and external objects). Ideally, for rigging, any simplified approach should also provide path independent deformations determined completely by a kinematic skeleton.
Accordingly, what is desired is a framework for the simulation of soft tissues that targets all aspects discussed above. Additionally, what is desired is to solve problems related to character skinning, some of which may be discussed herein, and reduce drawbacks related to character skinning, some of which may be discussed herein.